1. Field of the Invention
The present invention relates to cooling and refrigeration systems, and more particularly to an intermittent absorption system with a liquid-liquid heat exchanger that uses waste heat to reduce the need for solar energy and increase the coefficients of performance of intermittent absorption air-conditioning and refrigeration systems.
2. Description of the Related Art
Conservation of energy, namely electricity, in both the production and consumption sectors, is continuing to be a worldwide priority. One such area is in the development of air-conditioning and refrigeration systems. It is no surprise that the days, times, and locations requiring maximum cooling loads coincide with the days and times with the highest temperatures and locations with the hottest climates. Conventional air-conditioning and refrigeration systems are powered using electricity. In the areas with the hottest climates and during the days and times with the hottest temperatures, the use of electricity to power such air-conditioning and refrigeration systems becomes very expensive and inefficient.
Solar power can be utilized to provide power for refrigeration and air-conditioning systems. Absorption chillers, for example, can use solar energy to produce refrigeration. Absorption chillers can be classified in two different categories, namely, continuous operation systems and intermittent operation systems. The difference between the two systems lies in their mode of operation. For example, in continuous systems both generation and absorption of energy take place at the same time in a continuous manner, whereas in intermittent systems, the generation and absorption of energy do not take place at the same time. Instead the generation and absorption of energy follow each other intermittently within the operation of the system.
Compared to continuous systems, intermittent systems have an advantage of not requiring any solution pump for their operation. Although not requiring a solution pump, their coefficient of performance is still comparatively very low. The main reason for higher coefficient of performance of continuous systems is their ability to recover waste energy by employing a liquid-liquid heat exchanger. The ability to recover waste heat in continuous operation systems is due to the fact that both absorption and generation take place at the same time so that both hot and cold solutions are present during the operation at the same time, hence making it possible to recover waste energy.
However, for conventional intermittent systems, it is not usually possible to use a liquid-liquid heat exchanger simultaneously for waste energy recovery due to the unavailability of hot and cold solutions at the same time. The inability of conventional intermittent systems to use a liquid-liquid heat exchanger simultaneously to recover waste energy results in a significant increase in capital cost and a decrease in its coefficient of performance, therefore, making conventional intermittent absorptions systems cost prohibitive and not economically feasible.
Thus, an intermittent absorption system with a liquid-liquid heat exchanger solving the aforementioned problems is desired.